RE: Parallel Queries and CPU usage high

Looks like you are running out of CPU power to support parallelization.
Running at 100% is not a problem in itself, if there are no processes
waiting for the CPU (check sar output). With parallelization, the number of
processes will increase, depending upon the degree of parallelization used
by the queries from these users. If you set parallel_max_servers to a high
value, then all these extra processes will increase the load on the system.
If the queries perform sort operations, then those will use twice as many PQ
processes. If the degree of parallelization is set at table level, all
queries against it will try to use PQ by firing required number of PQ
processes, the only limiting factor being parallel_max_servers value. Try to
get more information on parallel_max_servers, parallel_min_servers and
parallel_min_percent parameters and the V$PQ_SYSSTAT view. That would help
you control the PQ operation in your database. If you need more information,
you may e-mail me off-line.

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Author: Deshpande, Kirti
INET: kirti.deshpande_at_verizon.com
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
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